This is a very bad idea for so many reasons it would take me forever to list them all. But here are a few:

1. no such loose federal arrangement would survive very long (remember the post-Soviet Commonwealth of Independent States?), so the plan leads to the dismemberment and partition of Iraq. This outcome is unacceptable to Turkey and Saudi Arabia and therefore will likely lead to regional wars.

2. The Sunni Arabs, the Da`wa Party and the Sadr Movement are all against such a partition, and together they account for at least 123 members of the 275-member parliament. Some of the Shiite independents in the United Iraqi Alliance are also against it. I would say that a slight majority in parliament would fight this plan tooth and nail. The US cannot impose it by fiat.

3. The Sunni Arabs control Iraq's downstream water but have no petroleum resources. If the loose federal plan ends in partition, the situation is set up for a series of wars of the Sunni Arabs versus the Shiites, as well as of the Sunni Arabs and some Turkmen versus the Kurds. Turkey, Iran and Saudi Arabia will certainly be pulled into these wars.

It is not good for the region to have a series of wars over Iraq. It is not good for the security of the United States, since those wars will probably involve pipeline sabotage by guerrillas and will likely disrupt Middle Eastern oil flows. (Did Americans like $3.20 a gallon gasoline and $300 a month heating bills? Would they like to try $15 a gallon gasoline? What do you think would happen to the world economy?)

Finally, I just don't believe that the Arab and Muslim worlds would ever forgive the US for breaking up Iraq, and there are likely to be reprisals if it happens.

Moqtada Sadr has no plans to rule over a third of Iraq. That may suit the Hakims, but they're already under pressure by the Sadrists. You split Iraq, you ensure a civil war.